I. Field of the Invention
This invention is directed to the field of telecommunications. More specifically, this invention is directed to eliminating an inoperable service node from a telephone call setup path.
II. Description of Related Art
Generally speaking, when a telecommunications switch that serves a given telephone number receives a call setup message seeking to establish a call with that number, the switch may pause call processing and signal to a service control point (SCP) to receive call processing guidance from the SCP such as in a telecommunications system implementing intelligent network functions. One such intelligent network is described in U.S. Pat. No. 6,728,783 to Scott et al., which is incorporated by reference herein. In providing the processing guidance, the SCP may refer to a service profile record for the called party, determine an action to take, and instruct the switch to handle the call accordingly. Intelligent networks may be implemented in any number of different communication systems, such as wireless communication networks (e.g., code-division-multiple access networks or global system for mobile communications), public switched telephone networks, or voice-over Internet Protocol networks. In such networks, an SCP is an entity that provides call processing guidance to other entities in the network (e.g., a communications switch).
Depending on the service profile record and/or for other reasons, the SCP might determine that the call destined to a given telephone number should be connected to a service node or other call-handling platform prior to connecting the call to the called telephone number and instruct the switch accordingly. In turn, the service node may carry out one or more functions (such as interacting with the calling party and/or executing call processing service logic) and then set up an outbound call connection to the originally called telephone number. Consequently, in this situation, the service node sits within the call path (e.g., voice path or trunk connection) from the calling party to the called party. Specifically, the voice path of the call would pass from the calling party to the service node and then from the service node to the called party. It will be appreciated, of course, that additional intermediate entities could sit within the call path as well.
An example of this scenario occurs commonly with prepaid telephone service. In particular, when a calling party seeks to place a call to a prepaid telephone subscriber, an SCP instructs the terminating switch to connect the call to a service node that is employed to monitor prepaid calling account balances. The service node then checks the account balance of the called party and, if it is sufficient, connects the call through to the called party. As the call progresses, the service node sits in the path of the call and may interject announcements (e.g., that the subscribers prepaid time is about to expire) or disconnect the call if the prepaid subscriber's balance becomes exhausted during the course of the call.
Another example of this scenario can occur in connection with a custom ring-back tone service. For this service, an SCP may also direct the terminating switch to connect a call to a service node. The service node then answers the call and plays a custom ring-back tone (such as music or a recorded voice message) to the calling party, while simultaneously placing an outbound call to the called party. When the called party answers, the service node bridges the calling and called parties together. With this service, the calling party hears music, the called party's voice, or any number of other possible custom ring-back tones, instead of a more conventional ring-back tone while waiting for the called party to answer.
In these and/or other scenarios, a problem may occur if the service node becomes unavailable, such as if the service node loses power or otherwise becomes inoperable and unable to handle calls. When such a situation occurs, the SCP would not know that the service node has become unavailable. Thus, the SCP will still direct the switch to connect calls to the unavailable service node (when such call routing would normally be appropriate). The switch would thus try to set up the call to the service node and would either (i) fail, in which case the calling party would receive a busy signal or dead air, or (ii) succeed, after which the service node would fail to set up the call to the called party, so the calling party would similarly receive a busy signal or dead air. In either case, due to the unavailability of the service node, the called party would never receive the call.